Process of treating the anode-mud resulting from electrolytic refining.



'which are subsequently UNITED STATES PATENT OFFICE.

rnocass or TREATING 1,049,013. No Drawing.

sulting from Electrolytic Refining, of which the following is a specificat on.

In the electrolytic refining of various metals such as lead or copper there is formed an anode mud which as arule consists chiefly of lead, antimony, copper, arsenic and 'prthr cious metals. This mud is generallygireated by means of suitable oxidizing agents and acids so as to convert it partly into soluble and partly into insoluble compounds, thus dividing it into two portions or groups sub-divided in turn and finally converted into pure metals or compounds. In the. methods practised hitherto the first'division into two groups resulted in the production of one group containing copper and arsenic in solution and a second group containing the other constituents. The separation of antimony from precious metals re uired a which I antimony was dissolved and thus removed.

Another'method used hitherto consisted in removing gold and silver by filtration after a preliminary chlorination of the mud and then dividing the metals remaining in solution into three groups by distillation, precipitation and filtration. Inasmuch as the chlorids of arsenic and antimony do not become volatile until a temperature far abovethe boiling point of water is reached, this subdivision or separation necessitated a preliminary evaporation or condensing of the solution and the redissolving of the distilla tion residue in order to separate the latter into constituents susceptih epf 'being precipitated and those not-yielding to such treatment. 1

My present invention relates to a method of treatin a substance or mud of the character specified above according to which the mud will be split up or subdivided into three groups by a single operation without any preliminary removal of any constitu-- ents and without-any necessity for evaporating or condensing solutions; these three groups are: A. Lead and precious metals.

B. Antimony and copper. C. Arsenic.

The roc'e'ss iscarned out for example by sub ecting the mud simultaneously to Specification of Letters Patent. Application filed December 26. 1911.

ment.

1 has been distilled over main; wn mLm, or srsctrrz, NEAR BERLIN, GERMANY.

THE ANODE-MUD RESULTING FROM ELECTROLYTIC REFINING'.

Patented Dec. 31, 1912.

Serial No. 667,786.

the action of sulfuric acid, hydrofluoric acid, and an oxidizing agent or oxidant; preferably the mud, ,in a mixture of diluted sulfuric acid and hydrofluoric acid, is heated for a considerable length of time to a temperature of about C., while passing a current of air through the liquid. The precious metals are not affected by this treatment,' but lead is transformed into the insoluble lead sulfate, copper and antimony are dissolved under formation of their sulfates and fiuorids; and arsenic is distilled overin the form of its fluorin compound and is then recovered by condensing the vapors- Co per and antimony are separated from t e insoluble residue by removing the latter by filtration and then washing it. The metals of the group A, that is to say, the precious metals and lead (in the form of lead sulfate) are separated in the well known manner by a metallurgical treat- From the solution of the metals in group B, I recover first copper and then antimony by electrolysis in' the well" known manner. Finally the fluorin compound of arsenic is preferably decomposed by the 'action of hydrogen sulfid, thus liberating .the hydrofluoric acid which is combined. witharsenic, and this liberated hydrofluoric acid together with any excess of such acid which is returned to the initial stage of the process.

By comparing the new process just described with the former processes mentioned at the beginning of this specification, it will be seen that my invention simplifies and cheapens considerably the treatment of the anode mud, the advantage of the new process residing chiefly in the fact that the subdividing of the original mud. into three groups of metals is accomplishedin a single operation without requiring the o3? iporation or condensing of the distillation residue.

Various modificationsmay be made without departing from the nature of my invention asset forth in the appended claims.

I- clainr as my invention:

1. In the treatment of arsenic bearing anode .mud resulting from electrolytic re-, fining, the proeessfwhich'consists in converting the arseni into a fluorin compound and distilling at a temperature below the boilingpoint of water.

2. .In the treatment of contains precious metals, lead, copper, antimo'ny and arsenic,i" theprocess which conanode mud which fate undissolved, while the second contains,

- copper and antimony as dissolved sulfates and two agent-some of Which it may be removed by distillation, the a I operation being conducted at a temperature and fiuorids, and the third contains arsenic in the form of a volatile distille'd fluoridQ 3. The process of se arating the constituentsof mixtures, whicfii consists in'treating the mixture simultaneously with an oxidant which has the property of bringing some ents into a dissolved condition, while the other has the property of bringing another portion of the mixture into a condition in sufiicient to effect distillation of the secondnamed agent and the portion of the mixture of the said constitu-- contained therein, but not suiiicient to remove the first-named agent and the sub stances contained therein.

4; The process ofseparating the constitu- I ents of mixtures, which consists in treating the mixture simultaneously with an oxidant 7 1 5 and two agents at a'tempe'rature intermediate betweenthe boiling points of said agents one of said agents having the property .0 -1 bringing a portion of the-constituents into a dissovled condition, whilethe other agent has the property of bringing another portion of the mixture into a condition in which it may be removed by distillationef In testimony whereofi-[I have hereuntoj --set my'hand'in the presence of two subscribe;

ing witnesses.

Witnesses HENRY HASPER, Wommmn HARRY 

